A rapid and negative spatial differentiation has been observed, especially in big cities in Turkey, after the 1950’s migration from the rural to the city, together with rapid increase in urban population and settlements in urban land with insufficient planning or infrastructures. As a consequence of this spatial differentiation it has become necessary to take all possible measures in every arena as well as the housing market as far as meeting the housing demand within a framework of planning, taking into consideration city characteristics and environmental conditions and in summary, establishing the balance between demand and supply. The 1999 earthquake has become a major factor affecting the housing market in Istanbul. August 17th, 1999 earthquake has been the turning point for the public to scrutinize the quality and safety of construction systems and geological location, especially in the housing market in Istanbul, where rapid increase of population and migration have been creating serious social disorders. In a very short time, changes in housing preferences with fear of an earthquake and new political and legal arrangements in the housing market have reflected in the urban environment. Shortly, urban development dynamics have changed with the earthquake. The purpose of the proposed ITU research project, is to analyze; changes in housing demand from a global perspective, in today`s Turkey and in Istanbul, evaluating the social, cultural, economical and political situation from a historical stand point; presenting the housing problem and its dimensions; the housing demand, and trying to determine how this demand is met by the market; developing solutions and recommendations, emphasizing the need for taking all necessary measures in meeting the housing demands of all levels in the society. The study is also to analyze questionnaire results (real estate agencies and households) and statistical data with the help of GIS (Geographical Information Systems) scrutinizing the changes in housing demand and housing problems. The earthquake in 1999 and the economic crises that took place afterwards affected the housing markets and the spatial distribution of real estate agents in the last ten years in Istanbul and the different socioeconomic structures of districts were also affected. The aim of this paper is, to scrutinize the role of Real Estate Agencies in these changes and to research the differentiation in the housing and real estate markets before and after the earthquake. In relation with this aim, socio-economic structures of households, housing production, differentiation in demand and supply in the housing market and distribution of real estate agencies have been investigated. The distribution of real estate agents will be examined with the help of GIS and the differentiation will be scrutinized for the 1995-2005 period. In this study, conducted with the purpose of investigating the spatial distribution of real estate agents, relations between demographic, physical and economic characteristics of districts were examined. Demographic data such as population and its rate of increase, density, number of households and physical characteristics such as land use, kinds of housing, wealth of districts, distance to city center, size, date of becoming districts and land value characteristics of districts have been researched and the distribution of real estate agencies have been analyzed. It has been observed that close relationships exist between demographic and physical characteristics of districts and distribution of real estate agents. A significant finding of this research has been that the differences in physical, demographical and economical characteristics of Istanbul’s districts show variations in the number and density of real estate agencies. According to the analysis, where population and number of households are high and districts are wealthier, there are a higher number of real estate agencies; where date of becoming a district is recent, the size of the district is large, the rate of population increase is high, and away from the city center, the number of real estate agencies is lower. According to the results of the analysis; old districts, which function as centers and sub-centers in which the real estate agents are concentrated; restructuring the existing stock in certain standards and construction of high quality houses in the new districts and districts located on the edges where the increase in the number of real estate agents is high and the demand increase after the earthquake are matters that need to be taken up urgently.